Lock washer



April 20, 1954 KNQHL 2,675,844

LOCK WASHER Filed April 23, 1952 INVENTOR.

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Patented Apr. 20, 1954 UNITED STATES TPATENT OFFICE LOCK WASHER Friedrich Karl Knohl, Chicago, Ill., assignor to Illinois Tool Works, Chicago, 111., a corporation of Illinois Application April 23, 1952, Serial No. 283,946

used which will accommodate itself to this variation. Likewise, itis not uncommoninapplications where a heavy duty Washer is required to employ a dished washer of considerable thickness. It is one of the important objects of the present invention to provide a new and improved dished lock washer having improved locking characteristics, as Well as a washer which will cost considerably less than washers heretofore available for the same purpose.

More specifically the invention contemplates a lock washer of the type referred to above, wherein the flexibility of the outer marginal looking sections of the washer is enhanced without impairing the requiredbody rigidity extending between said sections.

It is a further object of the present invention to produce a dished type lock washer as above referred to, wherein relatively thin sheet metal stock may be employed so as to afford the required flexibility of the locking sections along the outer margin of the washer, coupled with strengthened sheet metal stock extending between said sections designed to increase resistance to clamping forces acting against the washer. I

The foregoing and other objects and advantages will be more apparent from the following detailed description, when considered in connection with the accompanying drawing, wherein Fig. 1 is a plan view of, a dished lock washer which is representative ofone embodiment of the present invention;

Fig. 2.is a front elevational view of the lock washer shown in Fig. 1; I

Fig. 3 discloses the washer of Fig. 1 in central cross-section along the line 33 of Fig. 1 positioned between a clamping surface of a rotary threaded fastener such as a nut and a work sur 7 Glaims. (Cl. 151-35) face just prior to the tightening of the nut against I -nated generally by the numeral l0.

stock in strip form from which the washers of I the present invention may be very economicallyproduced;

Fig. 8 is a fragmentary plan view similar to'Fig. 5 '1, showing a slightly modified form of washer equipped with a strengthening flange in the vicinity of the ribs or bosses; and

Fig. 9 is a fragmentary perspective edge View of the washer of Fig. 8.

Referring now to the drawing more in detail, wherein like numerals have been employed to designate similar parts throughout the various figures, it will be seen that one embodiment of the invention contemplates a lock washer desig- This lock washer I0 is provided with a central aperture l2 defined by a plurality of circumferentially spaced locking prongs It extending radially inwardly from the inner margin of the washer body. In

the disclosed embodiment these prongs it are so deflected or twisted as to present locking teeth l6 adapted for clamping engagement by a rotary threaded fastener, such as the nut 86 shown-in Figs. 3 to 6, inclusive. project axially beyond the upper limits of the washer body in position to be engaged by the clamping surface of a nut or screw head.

The washer body which suports the prongs I lincludes circumferentially spaced relatively rigid sections 20 which are separated by relatively resilient or yieldable sections 22. The sections 28 are relatively rigid by'reason of the strengthening ribs or bosses 24 which extend tangentially with respect to a circle concentric with the washer axis. In other words, these strengthening ribs or bosses 24 extend generally in a circumferential direction along the washer body. By reason of the presence of the ribs 24, the circumferential 1 extent of the washer body determined by the length of these ribs is relatively rigid, as distin guished from the bodysections 22 extending be tween each pair of ribs. I

ally deflected teeth 26 provided at the opposed corners of radially extending lugs.

of a work piece 28 shown in the drawings. It

will be noted that in cross-section taken along" the line 3-3 of Fig. 1, as well as in cross-section taken'along the line 55 of Fig. l, thewasheri body is generally dished so as to permit considerable axial deflection when a clamping member such as the nut it is'tightenedfromthe position shown in Fig. 3 or 5 to the'position shown in Fig. 4 or.6, respectively. It is of the-utmost importance that the body portions 22be resilient These teeth I6 normally These teeth 26 are designed for locking engagement with a complementary work surface such as the surface because of their intimate association with the locking teeth 25. Thus, when the washer is clamped in position, the resiliency of the body portion 22 cooperates with the aggressive biting action of the teeth 26 to assure a flrm spring grip over the entire range of axial flexure of the washer.

It is of importance to note that while the, body portions 22 contribute the required yieldability to enhance the eiilciency of the locking teeth, the remaining areas of the washer body including the circumferentially extending bosses 22 are sufliciently rigid to lend the firm and effective resistance to clamping forces exerted against the washer. This arrangement makes it possible to employ relatively light gauge washer stock in order to obtain the required degree of flexibility in the washer body areas 22, and at the same time maintain the required resistance to the clamping action of the nut in the body sections or areas 20. Were it not for the presence of the circun ferentially extending ribs 24, it would not be possible toemploy the relatively light gauge readily flexible washer stock. Not only does the use of lighter gauge sheet metal washer stock contribute to the flexibilty in circumferentially spaced areas of the washer body, but it also makes possible considerable saving in cost manufacture. Heretofore, washers of this dished type were made of relatively heavy stool: in order to withstand severe load conditions, and obviously this stock of heavier gauge is considerably more expensive than lighter gauge material. Hence, the present invention not only makes possible a more efficiently operable dished type lock washer, but also contributes materially to savings in cost of manufacture.

It will also be apparent from the disclosure in Figs. 4 and 6 that the strengthening ribs 2 are designed to serve as abutments against which the clamping surface of the nut it may hear when the washer is finally tightened to the positions shown in Figs. 4 and 6. In this manner the ribs or bosses 24 cooperate to prevent complete flattening or untwisting of the washer prongs M.

In instances where increased rigidity is required in the area occupied by the ribs or bosses 24, flanges 303 are formed along the margin of the washer as shown in Figs. 8 and 9. These flanges depend from each washer margin adjacent a complementary boss 24. The flanges as cooperate with the bosses 24 in lending increased rigidity to the washer stool; in that area.

By having the external periphery of the washers shaped in accordance with the teachings, of the present invention, the ease with which the washers may be formed and stamped from sheet metal strip stool; is greatly facilitated. In this connection specific reference is made to the disclosure in Fig. 7 showing a fragmentary view of the washer stock in strip form fromwhich each of the washer members it! may be produced. By employing the straight line severance between peripheral contacting areas of the washer members, greater tool life is experienced.

From the foregoing it will be apparent that the present invention contemplates a novel and commercially desirable dished type lock washer. Considerable savings result from the use of lighter gauge material, and this lighter gauge material contributes materially to the resilient functioning of the external lock washer teeth. Likewise, the remaining portions of the washer body requiring greater resistance to clamping forces are strengthened by the circumferentially or tangentially extending ribs. As heretofore set forth, these ribs not only serve to increase resistance to clamping forces, but also-provide firm abutments when the washer is flattened to a considerable degree, thereby preventing complete untwisting or flattening of the internal washer teeth.

While for purposesof disclosure certain specific embodiments of the invention have been shown in the drawings,,it will be apparent that the invention is capable of other modifications and changes without departing from the spirit and scope of the appended claims.

The invention is hereby claimed as follows:

1. A look washer having an annular dished body, the-concave side thereof being adapted for application to a work surface, inner teeth carried by the inner margins of the body for lockingly engaging the clamping side of a screw head or nut, circumferentially spacedouter teeth projecting radially outwardly from the outer margin of the body for lockingly engaging a complementary work surface, a plurality of circumferentially spaced'ribs on said body located between the inner and outer margins thereof and of sufiicient elongation in a generally peripheral direction to substantially traverse the space between adjacent radially projecting outer teeth for increasing the strength of the body in that vicinity to resist forces tending to flatten the body, the adjacent ends of adjacent ribs beingspaced apart and terminating substantially in the vicinity of corresponding radial margins of said outer teeth and the portions of the body extending between r adjacent spaced rib ends being yieldable and positioned. adjacent complementary outer marginal teeth to enhance flexibility in the vicinity thereof whereby to increase theglocking effectiveness of the washer.

2. A look washer in accordance with claim 1, wherein the strengthening ribs are not less than three in number and are uniformly distributed around the Washer body.

3. A look Washer in accordance with claim 1, wherein the circumierentially spaced ribs project axially beyond'the convex side, of the body to provide an abutment for the clamping side of a screw head or nut after the dished body has been flattened to an extent predetermined by the distance tov which said ribs project axially.

i. A lock washer in accordance with claim 1, wherein the outer circumferentially spaced teeth are provided at the opposed corners of circumferentially spaced lug portions projecting radially outwardly from the washer body.

5. A look washer in accordance with claim 4, wherein the outer edge of each lug portion extending circumferentially between, each pair of teeth defines a straight line.

6. A look washer in accordance with claim 1, wherein each yieldable body portion is complemental to a pair of outer marginal circumferentially spaced teeth.

'7. A look washer in accordance with claim 1,

wherein a marginal flange, is provided inv the vicinity of each rib between adjacent outer teeth to lend, increased rigidity in, that area of the washer.

References Cited'in the file of this patent UNITED STATES PATENTS 

